Self-locking nut

ABSTRACT

This is a lock nut which is formed into a generally elliptical configuration or triangular configuration having arcuate walls, is then tapped and the resulting configuration is then further distorted.

United States Patent 1191 Wright May 1, 1973 [54] SELF-LOCKING NUT [56]References Cited [75] Inventor: Thomas B. Wright, Diamond Bar, UNITEDSTATES PATENTS A a. 1,966,613 7/1934 Cole 10/86 A Asslgneel TRWCleveland, Ohm 2,279,388 4 1942 Cox ..l0/86 A 2,370,352 2/1945Hosking.... ..l5l/22 [22] 1972 3,145,751 8/1964 Boots ..151 21 B [21]Appl. No.: 217,682

Primary Examiner-Charles W. Lanham Related Apphcauon Data AssistantExaminer-E. M. Combs [63] Continuation of Ser. No.- 12,80l, Feb. 19,1970, Alwrney-Gordon Needleman abandoned.

52 us. c1 "10/86 A, 151/21 B 1 ABSTRACT [51] Int. Cl. ..B2ld 53/24 h isa lock nut which is formed into a generally [58] Field of Search 10/86R, 86 A;

liptical configuration or triangular configuration having arcuate walls,is then tapped and the resulting configuration is then furtherdistorted.

1 Claim, 6 Drawing Figures Patented May 1, 1973 4 INVENTOR THOMAS B.WRIGH' ATTORNEY BACKGROUND OF THE INVENTION 1. Field of the Invention Abasic requirement for self-locking nuts having onoff cycles with a boltis approximately fifteen cycles. Most lock nuts do not greatly exceedthis requirement and as a matter of fact the maximum number of cycleswould be approximately 50.

The most popular method of forming a lock nut is to tap a drawn cylinderand then form it into an elliptical shape. The nut is then hardened tospring temper. When a screw or bolt is engaged with the nut it forcesthe nut into a shape resembling the original round shape with resultinglocking torque. This action is however quite harsh so that the screwand/or the nut wears rather rapidly, diminishing the amount of torqueafter each use. It is believed that the nut disclosed herein should becapable of many hundreds of cycles within the permitted torque range. Itwill probably range from a minimum of three hundred to a possiblemaximum of one thousand cycles.

Superior performance is also expected from the disclosed configurationbecause the walls of the nut should act more effectively as a springwith a lesser differential in force between the extremes of the fullyinstalled condition and the free position.

2. Description of the Prior Art There are several ways of deforming nutsto provide a locking action. The patent to Hosking U.S. Pat. No.2,370,352 discloses a nut which is formed before and after tapping. TheHosking device deforms the lip of a tubular extension in one direction,taps the extension and then squeezes the opposite walls (i.e. those atright angles to the original compressed walls). In this case the twodeformations are not additive so that in Hosking the thicker wall gripsthe bolt.

The Evans U.S. Pat. No. 3,353,581 is directed at a nut which is formedinto a generally triangular configuration prior to tapping. In this casethere is no second distortion whatsoever.

There is a group of patents which disclose nuts that are deformed aftertapping. Some examples of patents in this group are the patents toReiner U.S. Pat. Nos. 2,816,591; Beford Jr., 2,846,701; Skidmore2,923,339; Boots 3,145,751; and Dwyer 3,277,942.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a lock nut which has been additively distorted.

A further object of the present invention is to provide a nut which hasits aperture formed in a generally triangular configuration which isthen tapped.

A still further object of the present invention is to provide atriangular lock nut which is then tapped and finally distorted.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a top plan view of the blankof the first embodiment;

FIG. 2 is a top plan view of the lock nut after the first distortion andtapping;

FIG. 3 is a top plan view of the lock nut after the second distortion;

G. 4 is a top plan view of the blank of the second embodiment;

FIG. 5 is a top plan view of the lock nut of the second embodiment afterdistortion and tapping, and

FIG. 6 is a top plan view of the lock nut of the second embodiment aftersecond distortion.

DESCRIPTION OF THE PREFERRED EMBODIMENT There is shown in the drawings ablank comprising a tubular unthreaded sleeve 12 with an integralrectangular flange 14 extending outwardly at substantially right tanglesat an end thereof. The blank may be drawn or formed in any other wellknown way. The internal diameter of the sleeve 12 is larger than astandard nut internal diameter by a predetermined amount. Notches 12 arecut into each of the short sides of the flange 14. The tubular sleeve 12is subjected to a three jaw chuck which squeezes it for the majorportion of its height into the form of a triangle 12a or using two jawsinto an elliptical shape 12b. The shaped sleeve 12a or 12b is thenthreaded by an axial tap which cuts the inner wall deeper in some placesas at 18-18 and less deep in other places such as at 20-20. Consequentlythe threads are somewhat truncated and blunt edged as at 18-18 and quitesharp and full at other places such as 20-20. This threading operationis performed through the major portion of the height of the sleeve 12.Note that more material is removed at 20-20 thereby thinning the wall atthat point and increasing the wall flexibility. In other words thethread thus formed is a continuous thread which is of full depth at thecenter of the lands and which is of gradually decreasing depth in eitherdirection therefrom reaching a minimum depth at the apex of the floatsor lobes of the triangles.

After the sleeve has been threaded it is again deformed by squeezing thesides in again with a three jaw chuck if triangular as at 12c and with atwo jaw chuck if elliptical as at 12d. The distortion of the ellipticalconfiguration occurs on the major arcs of the nut. This seconddistortion imparts the locking features.

lclaim:

I. A method of forming a self-locking nut comprising: (a) forming acylindrical barrel from a sheet metal blank; (b) squeezing the barrelover substantially its entire length to distort the same into anintermediate form having a noncircular transverse cross-sectionalconfiguration; (c) tapping the barrel in said intermediate form toprovide a continuous thread of constantly varying effective depth alongeach convolution thereof; and (d) squeezing the barrel a second time todistort the same into a final form having the same basic geometrictransverse, cross-sectional configuration as the second form butdeviating appreciably further from the original cylindricalconfiguration than the second form and having a substantially morepronounced variation in effective thread depth than the intermediateform. I

I i i i l

1. A method of forming a self-locking nut comprising: (a) forming acylindrical barrel from a sheet metal blank; (b) squeezing the barrelover substantially its entire length to distort the same into anintermediate form having a noncircular transverse cross-sectionalconfiguration; (c) tapping the barrel in said intermediate form toprovide a continuous thread of constantly varying effective depth alongeach convolution thereof; and (d) squeezing the barrel a second time todistort the same into a final form having the same basic geometrictransverse, cross-sectional configuration as the second form butdeviating appreciably further from the original cylindricalconfiguration than the second form and having a substantially morepronounced variation in effective thread depth than the intermediateform.